By Jonathan Kaminsky
DARRINGTON, Washington, April 2 (Reuters) - Efforts to recover bodies from a Washington State mudslide that killed at least 28 people could be hampered in the weeks ahead if melted snow runs into a clogged river at the disaster site, officials said.
Workers on the mud pile in the foothills of the Cascade Mountains, northeast of Seattle, over the past two days have taken advantage of sunny skies and slowly receding water, but more rain is expected on Thursday and is forecast to last through Sunday.
The official death toll from the slide, based on the number of victims whose remains have been sent to the coroner's office, rose to 28 on Tuesday, up from 24 a day earlier, while 20 people were still listed as missing.
The March 22 slide was triggered when a waterlogged hillside caved in above the Stillaguamish River.
A torrent of mud roared over the riverbanks and across state Highway 530, engulfing some three dozen homes on the outskirts of the town of Oso.
The mudslide clogged the Stillaguamish River, which in the following days cut a slow-moving channel through the mud and debris. But snow melting on the Cascade Mountains is expected pour through that channel, possibly flooding the mud pile site.
Sections of the slide area, already under 25 feet of water and thought to contain human remains, could within three to four weeks become submerged beneath more than 100 feet of water if no channel to divert the partially dammed river is built, said Mike Asher, an area fire chief acting as the head of operations for the east side of the disaster zone.
"There's a lot of snow left on the mountains surrounding the valley," Asher said. "We're going to start facing runoff issues from that in the very near future."
The U.S. Army Corps of Engineers is working on a plan to dig a river channel, likely to be accompanied by levies, to keep the muddy, contaminated disaster site cordoned off, Asher said. If the diversion goes wrong, the river could flow west down Highway 530, flooding both the road and homes alongside it, he said.
Meanwhile, no signs of life have been detected since the day of the slide, when eight injured people were rescued.
"Where we find a lot of log jams and that type of area, that's where we're finding the human remains," recovery team supervisor Steve Harris told reporters on Tuesday, referring to places where most debris had collected after trees and logs crashed through homes.
The search-and-recovery force included a mix of firefighters, National Guard troops, U.S. Army soldiers and civilian volunteers, some from the local community, in an area that supervisors have mapped out in a three-dimensional grid.
The Snohomish County Medical Examiner's Office said 22 of the confirmed fatalities have now been identified, including a 4-month-old girl and two other children aged 5 and 6. (Editing by Alex Dobuzinskis and Louise Ireland)